Reaction of 1, 1-Di-p-methoxyphenyl-2, 2-dinitroethylene and 1, 1-Di-O-methoxyphenyl-2, 2-dinitroethylene with 1-Benzyl-1, 4-dihydronicotinamide： Evidence for Concerted Electron-hydrogen Atom Transfer Mechanism

1,1-Di-p-methoxyphenyl-2, 2-dinitroethylene reacts with 1-benzyl-1, 4-dihydronicotinamide (BNAH) in deaerated acetonitrile to give 1,1-di-p-methoxyphenyl-2, 2-dinitroethane,while 1,1-di-O-methoxyphenyl-2, 2-dinitroethylene fails to react with BNAH under the same conditions, which provides evidence for a concerted electron-hydrogen atom transfer mechanism.     

李春艳1,李建华1,申贵隽2*

氰化物是一种快速、剧毒的化合物,能够引起组织衰竭以至机体死亡。氰化物一旦污染环境及食用源,会严重危害人体健康,当吸入或口服较大剂量氰化物时,会引起“闪电式”骤死,中毒者在10~60S内突然发出尖叫随即昏倒,出现强直性与阵发性痉挛,2-3min后呼吸停止而死亡[1]。因此加强对氰化物检测是一项重要的安全检测指标,为此,建立准确、快速,特别是能用于现场操作的氰化物测定方法有重要意义。     

有机化学中S_N2,S_N1,E2,E1反应的相互竞争关系

有机化学中的SN2,SN1,E2,E1反应在学习中有着重要的作用,同时也是学习中易混淆的知识点。通过总结它们的反应机理、反应影响因素和反应相互竞争关系图,并利用竞争关系图解答了一些典型考研真题,方便读者理解和掌握SN2,SN1,E2,E1反应的相互竞争关系。     

Ab initio Study of H2O–HCl (1:1, 1:2, 2:1) Complexes

This paper reports on an ab initio (6-31G**) study of 1:1, 1:2, and 2:1 (H₂O) _n (HCl) _m complexes. Stable configurations of the 1:2 and 2:1 (H₂O) _n (HCl) _m complexes and their geometrical and energy characteristics were determined. The vibrational analysis of the complexes was carried out. The effect of hydrogen bonding due to S₁S₀ and T₀T₁ electronic excitations is considered.     

Solubility of Oxygen in Some 1-1, 2-1, 1-2, and 2-2 Electrolytes as a Function of Concentration at 25°C

The solubility of oxygen has been measured in a number of electrolytes [(LiCl, KCl, RbCl, CsCl, NaF, NaBr, NaI, NaNO₃, KBr, KI, KNO₃, CaCl₂, SrCl₂, BaCl₂, Li₂SO₄, K₂SO₄, Mn(NO₃)₃)] as a function of concentration at 25°C. The solubilities, mol (kg-H₂O)^–1, have been fitted to a function of the molality m (standard deviation < 3mol-kg^–1)

Crystal Structure of 1, 1-Dichloro-la, 3-diphenyl-1, la, 2, 3-tetrahydro-azirino [2, 1-d ] [1, 5]benzothiazepine (C_(22),H_(17)Cl_2NS )

1INTR0DUCTI0NBenzoheteroazepinecompoundsareimportantpharmaceuticalagents"-".Inre-centyears,ithasbeenfoundthatbenzoheter0azepinetricyclicderivatives,especiallythosefusedwithotherfiveorsix-memberedheterocycle,area1soofpotentialphar-maceuticalinterestst4-6j.Hence,muchattentionhasbeenpaidtothesynthesesofthem,suchasl,3-oxazino[3,2-djt1,5jbenzothia/diazepin-l-onet"'J,1,2,4-tria-zolo[4,3-dj[1,5jbenzothia/diazepine"',1,2,4-oxadiazolo[4,5-dj[l,5jbenzothia/diazepine',',andsoon.Meanwhiletheirstructur…     

Photo-induced Coupling Reaction of 1, 1-Diphenyl-2, 2-dicyanoethylene with 10-Methyl-9, 10-dihydroacridine

In a previous communication1, we reported a novel photo-induced coupling of 9-fluorenylidenemalononitrile 1 with the coenzyme NADH model 10-methyl-9, 10-dihydroacridine (AcrH2) to give 9-dicyanomethyl-9-(10-methyl-9-acridinyl)fluorene and proposed a mechanism involving photo-induced electron transfer-proton transfer and radical coupling. This is a scarce mechanism for the reaction of NADH models2, which usually takes place by a formal hydride transfer pathway3. In view of the novelty of t…     

Grignard Addition to Quinoxalinium Salt： Synthesis of 1, 2-Dihydroquinoxaline and 1, 2, 3, 4-Tetrahydroquinoxaline Derivatives

Nucleophilic addition of organometallics to imines or iminium ion has received greatattention in recent years, especially in the field of asymmetric synthesis1. Addition ofthe nucleophilic reagents to quinoxalines was proved to be a useful method for thes…     

CRYSTAL STRUCTURE OF 2, 4-DITHIONE-3-AMINO-1, 3, 2-OX-AZAPHOSPHORINEBENZO-2-THIONO PYRIDINIUM

<正> The structure of title compound [C7H6N2OPS3]-·[HNC5H5]+ was determined by x-ray diffraction. It belongs to monoclinic system with space group P21/a, a = 16.745(2), b= 8.563(2), c=21. 050(5)(?), β=93.32(1)°, V= 3013. 6(?)3, Z = 8, Mr = 341. 4, F (000) = 1536, Dc=1. 504 g. cm-3,μ= 53. 0 cm-1. The crystal is composed of discrete cations C5H5NH+ and anions CrH6N2OPS3-. There are two pairs of the cations and the anions in each asymmetric unit. The stability of the anion is increased by the formation of (d-p)π bonding involving the 3d orbital of the P atom and the lone electron pairs of the S atoms.     

DIELECTRIC PROPERTIES OF 1, 2-POLYBUTADIENES

The dielectric permittivity and loss tangent of 1,2-polybutadienes with different chain structures were determined as a function of temperature from-180℃ to 100℃ at different frequencies, and the frequency and structure dependence of the dielectric propertie of 1,2-polybutadienes have been investigated. It is found that a maximum of the permittivity occurs in the glass-transition region. The width of the glasstransition peak increases with increasing frequency while its height has little change. With a rise in the content of 1,2-units, the permittivity decreases and the height of the glass-transition peak slightly grows. A maximum of the width of the glass-transition peak appears when the content of 1,2-units is about 45%. Both the permittivity and dielectric loss drop down as the growth of the content of syndiotactic 1,2-units.     

A_a_1,A_a_2-B_b_1B_b_2缩聚反应的固化理论

本文讨论了A_(a_1),A_(a_2)-B_(b_1)B_(b_2)型缩聚反应的固化理论。给出了溶胶-凝胶分配公式、凝胶化条件、分布函数及适合固化全过程的高分子矩的循环公式和k次矩的解析表示式。     

DiastereoselectiveandEnantioselectiveSynthesisof(1S,2S)-2-Ethyl-1-aminocyclopropaneCarboxylicAcid

During the last decade, 1-aminocyclopropanecarboxylic acid and its derivatives (ACCS) have attracted increasing attention of organic and bioorganic chemists due to their outstanding biological properties, ranging from antimicrobial, insecticidal, plant growth and fruit ripening controls, etc.1. Moreover, the three-membered carbocycle provides building blocks of unprecedented synthetic potential because it undergoes selective ring opening, ring enlargement or cycloaddition reactions2. The mo…     

Preparation and properties of the systems Co1−xRhxS2, Co1−xRuxS2, and Rh1−xRuxS2

Members of the systems Co_1−xRh_xS₂ (0 ≤ x ≤ 0.6) were prepared, and their crystallographic and magnetic properties studied. The observed ferromagnetic moments for compositions where x ≤ 0.2 indicate a ferromagnetic alignment between Co(3d⁷) and Rh(4d⁷) electrons. This is the first observation of localized behavior of 4d electrons in the pyrite structure. Members of the systems Co_1−xRu_xS₂ (0 ≤ x ≤ 1) and Rh_1−xRu_xS₂ (0.5 ≤ x ≤ 1) were also prepared and their crystallographic and magnetic properties studied. From comparison with the Co_1−xRh_xS₂ system, it appears that the 4d electrons of Rh(4d⁷) are localized in the presence of Co(3d⁷) but are delocalized in the presence of Ru(4d⁶). The magnetic susceptibility of the Co_1−xRu_xS₂ system is sensitive to the homogeneity of the products and indicates that Ru(4d⁶) behaves as a diamagnetic ion.     

1, 1, 2, 3-四氯丙烷乳液消除反应的动力学研究

研究了1,1,2,3-四氯丙烷的乳液消除反应动力学.此反应是二级反应,主要产物是1,1,3-三氯丙烯-2,并有少量顺式及反式-1,2,3-三氯丙烯.从实验发现一系列独特的界面反应特征:(a)乳液消除反应速度常数-表面活性剂浓度图的实验点符合折线关系,折线交点落在某一临界表面活性剂浓度上;(b)表观活化能随表面活性剂浓度的增高而先呈线性增大,达极大值后又急剧下降,最后趋近极限值;(c)表观速度常数K_td几乎不随分散相对分散介质体积的分数变化而改变;(d)反应速度常数的对数随水相离子浓度对数的增大而下降.     

Synthesis and Crystal Structure of 2-Amino-1, 1-diferrocenylethanol

2-Aminoalcohols are useful intermediates in organic chemistry, for example, they serve for the synthesis of various heterocycles1, chelate complexes2, and for the ring expansion of cycloalkanones3. 2-Aminoalcohols containing ferrocene as bidentate ligand may be converted into multinuclear compounds. Several methods for the preparation of 2-aminoalcohols have been developed including reduction of the trimethylsilyl cyanohydrins4 or β-nitromethyl alcohols5 and treatment of the epoxides with a…     

Theoretical study on the substitution reactions of fluorosilylenoid H2SiLiF with SiH3XH n−1 (X = F,Cl, Br,O, N; n = 1, 1, 1, 2, 3)

The substitution reactions of H₂SiLiF (A) with SiH₃XH _n?1 (X = F, Cl, Br, O, N; n = 1, 1, 1, 2, 3) have been studied using DFT and ab initio methods. The results indicate that the substitution reactions of A with SiH₃XH _n?1 proceed via two reaction paths, I and II. The following conclusions emerge from this work. (i) The substitutions of A with SiH₃XH _n?1 are nucleophilic reactions and occur in a concerted manner. Path I is more favorable than path II. The substitution barriers of A with SiH₃XH _n?1 for path I decrease with the increase of the atomic number of X for the same period systems, whereas the barriers increase with the increase of the atomic number of X for the same family systems. (ii) The substitution products are H₂SiFSiH₃ and LiXH _n?1. If the H atoms in SiH₃ of SiH₃XH _n–1 are substituted by different atoms or groups, silanes H₂SiFSiH₃ obtained via paths I and II would be enantiomers. (iii) All the substitution reactions of A with SiH₃XH _n?1 are exothermic.     

SYNTHESIS AND STRUCTURE OF ADDUCT OF 1, 9-DIHYDRO-8,9-DIPHENYL-1, 2, 4-TRIAZOLO [4, 3-d] 1, 2, 4-TRIAZINE-3, 5-DITHIONE WITH TRIETHYLAMINE

<正> C16H13N5S2· (C2H5)3N: Mr = 440. 64, monoclinic, space group C2/c with a = 18.956(7)(?), b = 12. 866(7)(?), c = 20. 830(9)(?) , β=115. 63(3)°; Z=8; V = 4580(7)(?)3; Dc = 1. 278gcm-3; F (000) = 1872, μ= 2. 423cm-1 (MoKa). Final R is 0. 069. C16H13N5S2is non-planar with two rings, a five-member and a six-member with conformations of envelope and twist boat forms respectively, and the two substituted phenyl groups are in equatorial and axial positions.